Sir.—The article by Venkataraman et al1 described late infantile tetany and secondary hyperparathyroidism presumably due to the high phosphorus load in humanized cow milk formula. The letter from Bancroft2 described an additional case of this type of late hypocalcemic tetany, and he wondered if other cases had been seen. I wish to report late-onset tetany with hypocalcemia and hyperphosphatemia in two sisters that was similar in course to that described by Venkataraman et al and Bancroft, but in which a significant factor was maternal hyperparathyroidism and hypercalcemia.
Patient Reports.—Patient 1.—A 2900-g female neonate, the product of an uncomplicated term pregnancy, labor, and delivery, was born to a gravida 3, para 3 mother. After an uneventful hospital course, she was discharged home on a regimen of a humanized cow milk formula (Similac, Ross Laboratories, Columbus, Ohio). When the neonate was 9 days old, the mother noted